That many goalkeepers will definitely be very wasteful for a team because Chelsea will only use a few and it would be more ideal if Chelsea could sell half of that number to other teams and buy some other defenders to fill their defense to make it better.
I don’t know what Chelsea is doing with so many goalkeepers when they can only make use of one in a match. I don’t really think goalkeepers should be what Chelsea will be fighting for right now, there are other positions where Chelsea is performing poorly that they need to fix. Chelsea's defense is just too poor, it was just too easy for their opponents to penetrate during the preseason matches. I think they need to fix that, because no matter how good a goalkeeper is, if the defense is poor, then people will think the goalkeeper’s performance is poor. When Chelsea are singing, they should focus on quality players and not just signing random players.
It is not only about many goalkeepers, but also Chelsea have so many players that are playing the same positions. With the number of players Chelsea have now, they can form about three squads from them, but still, their performance is very poor, and they keep signing more. If it is possible, Chelsea need to sell some of these players and sign most important quality positions especially defenders, as you said.
Even with the many players Chelsea have, it can cause confusion for the head coach because he may not fully focus on the important players. He may be trying to rotate them to see their ability, but this can cause him not to discover one great squad. Signing players is a good thing, but when there are many sometimes it may be bad, it is very possible that the head coach may not give each player time to discipline and encourage them. I think it was many players in Chelsea that first caused Pochettino to loses match at the beginning as it was signed as head coach, But later, when he started focusing on one squad, he began to see improvement.